Rock drill rotation selection mechanism



Aug. 11, 1964 M. woRMAN 3,143,931

ROCK DRILL ROTATION SELECTION MECHANISM Filed Dec. 5, 1962 I 2 heets-Sheet 1 INVENTOR MART/N WORMAN F/G. BY

ATTORNEY @Mw-TW Au 11, 1964 M. WORMAN 3,143,931

ROCK DRILL ROTATION SELECTION MECHANISM Filed Dec. 5, 1962 2 Sheets-Sheet 2 WEAKE SPRING g v v t ST 3 SP 6 INVENTOR MgRT/N WORM/V 9M w .TM

ATTORNEY United States Patent 3,143,931 ROCK DRILL ROTATION SELECTION MECHANISM Martin Worman, Phillipsburg, N.J., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jersey Filed Dec. 5, 1962, Ser. No. 242,397 4 Claims. (Cl. 91-467) This invention relates generally to rock drills of the type containing a rifle bar for utilizing the reciprocation of the percussive piston of the drill to intermittently and unidirectionally rotate the drill steel or bit of the drill. In particular, this invention relates to an improved means for selectively controlling the rifle bar mechanism to cause it to rotate the drill bit in either rotary direction or to stop the rotary movement of the drill bit altogether.

It is conventional to provide a rock drill having a rifle bar rotation mechanism including two sets of pawls, each of which is used alternately. On set of pawls locks the rifle bar against rotating in one direction and the other set locks it against rotating in the other direction. It is also conventional to provide a manual means for operating a ring or sleeve to move the two sets of pawls to alternate inoperative positions. The principal object of this invention is to provide a power-operated mechanism which can be controlled at locations remote from the drill to cause the rifle bar to drive the drill bit in a selected rotary direction or to stop the drill bit rotation altogether.

Further important objects include the following: to provide a rifle bar rotation selection mechanism which is fluid actuated and which automatically returns to a predetermined position when the fluid pressure is released; and to provide a fluid pressure reciprocating actuator which automatically and accurately returns to an intermediate position when its fluid pressure is released.

These objects are attained generally by providing a rock drill raving a rifle bar with a three-position reciprocating fluid actuator or motor connected to the rotation selection mechanism of the rifle bar to selectively cause it to rotate the drill bit in one direction or the other or to stop the rotation altogether and to arrange the actuator so that it automatically returns to its intermediate position when its operating fluid is shut off.

The invention is illustrated in the drawings wherein:

FIG. 1 is a vertical axial section through the upper end portion of a rock drill utilizing the concepts of this invention;

FIG. 2 is a section taken on line 2'2 of FIG. 1;

FIG. 3 is a plan view of the upper end of the rock drill of FIG. 1 with portions cut away and illustrating the fluid actuating system for operating the rotation selection mechanism of the drill; and

FIG. 4 is a section similar to FIG. 2 showing one set of rifle bar pawls in an operative position.

Conventional Structure The rock drill 1 shown in the drawings conventionally includes a tubular body 2 containing a reciprocating percussion piston 3, a backhead 4 fixed to the rear end of the body 2 and having an air inlet 5 adapted to receive air pressure, and a sleeve valve 6 disposed between the body 2 and the backhead 4 for alternately admitting the air pressure in the inlet 5 to the opposite ends of the piston 3 for reciprocating it. All of the foregoing is well known in this art and, therefore, is illustrated in a general manner,-without showing detailed structure.

The backhead 4 contains a rifle bar 8 rotatably mounted therein and extending forwardly to slidably engage a rifle nut 9 fixed to the rear of the piston 3. The rifle ice bar 8 carries helical splines 10 engaging corresponding flutes in the rifle nut 9 whereby the piston 3 is caused to rotate relative to the rifle bar 8 as it reciprocates. The rear end of the rifle bar 8 carries a gear or ratchet wheel 11 which is adapted to be engaged by alternate sets of pawls 12 and 13. Looking at FIG. 2, the pawls 12 prevent the rifle bar 8 from rotatingin a clockwise direction and the pawls 13 prevent it from rotating in a counter clockwise direction. The pawls 12 and 13 are pressed against the gear 11 by fluid-pressure actuated plungerS 14 and are selectively prevented from engaging the gear 11 by a slotted ring or sleeve 15.

As seen in FIG. 2, the ring 15 can be located in an intermediate or center position wherein it prevents all of the pawls 12 and 13 from acting on the gear 11 wherein the rifle bar 8 is free to turn in both directions, or the ring 15 can be moved to each side of its center position to cause either of the sets of pawls 12 and 13 to act upon the rifle bar gear 11, which would latch the rifle bar 8 against rotating in one or the other rotary direction.

As is well understood in the art, the latching of the rifle bar 8 against turning in one direction will cause the piston 3 to intermittently and uni-directionally rotate in the opposite direction as it reciprocates. The piston 3 is keyed to the chuck (not shown) holding the drill bit (not shown) so that the rotation of the piston 3, correspondingly rotates the drill bit. For readers who are new to the rock drill art, reference is made to US. Patent No. 2,910,046 for a more detailed description of the foregoing conventional structure. Since the foregoing structure is well known and does not form any part of this invention, it is believed that the foregoing brief description is suflicient for an understanding of the invention.

Invention The sleeve or ring 15 is rotated between its selective positions by a vertical shaft 18 journaled in the backhead 4 and carrying a small spur gear 19 which is geared to external gear teeth 20 carried by the pawl latch ring 15. The top of the shaft 18 carries a handle or knob 21 which can be manually turned by an operator to move the ring 15 to a desired position. The manual handle 21 is the conventional device for performing this job.

In accordance with this invention, the backhead 4 is further provided with a reciprocating fluid-operated motor 23 for turning the shaft 18. Looking at FIG. 3, the motor 23 includes a transverse bore 24 extending at right angles to the shaft 18 and containing a portion of the spur gear 19. A piston 25 is slidably mounted in the bore 24 and includes the opposite end faces 26 and 27. The intermediate portion of the piston 25 is cut away and provided with rack teeth 28 engaging the spur gear 19 whereand 32. Thus, fluid pressure admitted into either of these chambers 31 and 32 will urge the piston 25 toward the other chamber.

A light coil spring 33 is located in the chamber 31 between the end face 26 of the piston and outer end of the chamber 31. The spring 33 is lightly loaded so that it urges the piston 25 toward the other chamber 32.

The chamber 32 contains a heavier coil spring 34 which is also loaded and which is disposed between a washer 35 and the outer end of the chamber 32. The washer 35 is larger than the piston 25 and slides in an enlarged portion 36 of the bore 24. The enlarged portion 36 of the bore 24 forms an annular shoulder 37 which the washer 35 is pressed against by the heavy spring 34 when the piston 25 is either in its intermediate position, shown in FIG. 3, or is moved further toward the chamber 31. Thus, the bias force of the heavy spring 34 is limited to acting on the piston 25 for only a portion of its travel. For example, looking at FIG. 3, when the piston is moving toward the left and the Washer 35 seats on the shoulder 37, the spring 34 is prevented from expanding further and the spring 34 no longer acts on the piston 25.

The end face 27 of the piston 25 contains a central projecting stem 38 which is slidable in the hole in the washer 35 for aiding in holding the washer 35 in proper alignment in the bore 24. The outer end of the chamber 32 is formed by a cap 39 threaded to the backhead 4 for purposes of assembly and disassembly of the motor 23.

It should be noted that when fluid pressure is vented from both chambers 31 and 32, the piston 25 returns exactly to its intermediate position, shown in FIG. 3, as a result of the two springs 33 and 34. Since the heavy spring 34 is stronger that the light spring 33, the heavy spring 34 can easily move the piston 25 to the left as shown in FIG. 3 until the washer 35 seats against the shoulder 37. Thereafter, the only spring force acting on the piston 25 is provided by the light spring 33 and it holds the piston in its intermediate position.

FIG. 3 schematically shows a system for selectively admitting fluid pressure to either of the chambers 31 and 32 of the motor 23. This system includes a three-position valve 41 having a handle 42. Fluid pressure, such as air pressure, is supplied to the valve inlet 43 and the two outlets 44 and 45 are connected by corresponding hoses 46 and 47 to ports opening into the chambers 31 and 32.

In the position of the valve 41 shown in FIG. 3, the valve core 48 closes the pressure inlet 43 and both of the outlets 44 and 45 are vented to atmosphere by the valve vents 49. Thus, the motor piston 25 will be in its intermediate position shown in FIG. 3. Turning the valve handle 42 in either direction for about 30 degrees will supply fluid pressure to one of the hoses 46 and 47 while continuing to vent the other hose. Thus, the motor piston 25 will be driven in a direction away from whichever chamber 31 and 32 is supplied with fluid pressure. It is believed that this operation is obvious without further explanation.

When the piston 25 is in its intermediate position shown in FIG. 3, the pawl latch ring 15 will be in its center position, as shown in FIG. 2, wherein both sets of pawls 12 and 13 are held in inoperative positions. Movement of the piston 25 to either of its outer positions will turn the ring 15 to unlatch one set of pawls, as shown in FIG. 4. The pawl latching and unlatching operation is the same whether performed by the motor 23 or the manual handle 21.

Although a preferred embodiment is shown and described in detail, it will be understood that the invention is not limited merely to this embodiment but contemplates other embodiments and variations which utilize the concepts and teachings of this invention.

Having described my invention, I claim:

1. In a rock drill containing a rifle bar and rotation selection means adapted to be selectively moved to various positions for causing the rifle bar to rotate the drill bit in either rotary direction or to stop the rifle bar from rotating the drill bit, the combination comprising:

(a) a fluid-operated motor operatively connected to said rotation selection means for moving said means to its various selective positions, said motor being movable to three positions including two end positions and an intermediate position;

(b) fluid means connected to the opposite ends of said motor for selectively applying fluid pressure to either of said ends to move the motor to its end position remote from the motor end receiving fluid pressure;

(0) spring means in said motor arranged to return said motor exactly to its intermediate position when the fluid pressure is shut off to both ends of the motor and both ends are vented;

(d) said motor including a reciprocating piston slidably movable in a cylinder;

(e) said spring means including a spring positioned in each end of said cylinder between the adjacent ends of the piston and the cylinder for urging the piston inwardly toward the other end of said cylinder;

(f) abutment means in said cylinder positioned to engage and stop the further expansion of one of said springs when said piston is in its intermediate position; and

(g) said one spring being stronger than the other spring at the opposite end of said cylinder.

, 2. The combination of claim 1 wherein:

(a) said abutment means includes a shoulder formed on the interior of the cylinder;

(b) and said one spring abuts a washer arranged to engage said shoulder when said piston is in its intermediate position.

i 3. A reciprocating fluid-operated motor including:

(a) a cylinder adapted to alternately receive fluid pressure introduced into its opposite ends;

- (b) a piston slidably mounted in said cylinder;

v 4. The motorof claim 3 wherein:

(a) said cylinderincludes an enlarged bore in its end portioncontaining said stronger spring;

(b) a washer is slidably mounted in said enlarged bore and adapted to engage one end of the bore when said piston is in its intermediate position;

(c) and said stronger spring is located to urge said washer against said one end of said enlarged bore.

References Cited in the file of this patent UNITED STATES PATENTS Sanders Q. Sept. 15, 1885 Kelly Jan. 25, 1938 Wiedmann July 20, 1943 Osgood Dec. 14, 1943 Lear Oct. 10, 1957 Morrison Oct. 2, 1962 Osgood Oct. 23, 1962 

1. IN A ROCK DRILL CONTAINING A RIFLE BAR AND ROTATION SELECTION MEANS ADAPTED TO BE SELECTIVELY MOVED TO VARIOUS POSITIONS FOR CAUSING THE RIFLE BAR TO ROTATE THE DRILL BIT IN EITHER ROTARY DIRECTION OR TO STOP THE RIFLE BAR FROM ROTATING THE DRILL BIT, THE COMBINATION COMPRISING: (A) A FLUID-OPERATED MOTOR OPERATIVELY CONNECTED TO SAID ROTATION SELECTION MEANS FOR MOVING SAID MEANS TO ITS VARIOUS SELECTIVE POSITIONS, SAID MOTOR BEING MOVABLE TO THREE POSITIONS INCLUDING TWO END POSITIONS AND AN INTERMEDIATE POSITION; (B) FLUID MEANS CONNECTED TO THE OPPOSITE ENDS OF SAID MOTOR FOR SELECTIVELY APPLYING FLUID PRESSURE TO EITHER OF SAID ENDS TO MOVE THE MOTOR TO ITS END POSITION REMOTE FROM THE MOTOR END RECEIVING FLUID PRESSURE; (C) SPRING MEANS IN SAID MOTOR ARRANGED TO RETURN SAID MOTOR EXACTLY TO ITS INTERMEDIATE POSITION WHEN THE FLUID PRESSURE IS SHUT OFF TO BOTH ENDS OF THE MOTOR AND BOTH ENDS ARE VENTED; (D) SAID MOTOR INCLUDING A RECIPROCATING PISTON SLIDABLY MOVABLE IN A CYLINDER; (E) SAID SPRING MEANS INCLUDING A SPRING POSITIONED IN EACH END OF SAID CYLINDER BETWEEN THE ADJACENT ENDS OF THE PISTON AND THE CYLINDER FOR URGING THE PISTON INWARDLY TOWARD THE OTHER END OF SAID CYLINDER; (F) ABUTMENT MEANS IN SAID CYLINDER POSITIONED TO ENGAGE AND STOP THE FURTHER EXPANSION OF ONE OF SAID SPRINGS WHEN SAID PISTON IS IN ITS INTERMEDIATE POSITION; AND (G) SAID ONE SPRING BEING STRONGER THAN THE OTHER SPRING AT THE OPPOSITE END OF SAID CYLINDER. 